Electron discharge device of the magnetron type



July 12, 1949.

Filed Jan. 11, 1945 //v Max/r04. 619/1 1. W 550mm,

Patented July 12, 1949 UNITED STATES i ATENT OFFICE ELECTRON DISCHARGEDEVICE OF THE MAGNETRQN TYPE Application January 11, 1945, Serial No.572,334

1 Claim.

This invention relates to electron discharge devices, such asmagnetrons, for example, and more particularly to those of smalldimensions and relatively low power.

One of the objects of the present invention. is to provide an electrondischarge device of the general type above referred to in which certainparts are preliminarily assembled and secured in the correct relativepositions they are to occupy in the completed device, the resultant unitthen being mounted in the device.

Another object of the present invention is to provide an electrondischarge device of the general type referred to having a specialarrangement of coaxial line for conducting the oscillations generated bythe device out of the latter.

These and such other aims and objects of invention as may hereinafterappear will b best understood from the following description taken inconnection with the accompanying drawing of one embodiment of theinvention herein given for illustrative purposes.

In the drawing:

Fig. 1 is a vertical section on line l--l of Fig. 2 of an electrondischarge device incorporating one illustrative embodiment of theinvention;

Fig. 2 is a horizontal section on line 22 of Fig. 1;

Fig. 3 is a vertical section on line 33 of Fig. 2; and

Fig. 4 is a horizontal section on line l4 of Fig. 1.

The illustrative embodiment of the invention shown in the drawingcomprises an anode struc ture consisting of a cylinder 2 and a controlwall 4 projectin from its inner surface and provided with a centralcircular aperture 6, to the wall of which is soldered a plurality ofradially disposed, suitably spaced, plates or arms 8. (See Fig. 4.) Saidcylinder 2 and wall 4 will preferably be made of copper. The said plates8 may be stamped out of a sheet of highly conductive copper and theirinner ends constitute anode faces I which form electron-receivingportions and cooperate with the cathode l i having its ac tive portionl2 supported substantially centrally of and coextensive with said anodefaces. Pole pieces l4 and I6 are provided at opposite sides of saidaperture 6 and concentrically with the latter. In accordance with thepresent invention said anode structure is supported b electricallyconductive rods I8 which are sealed through porcelain seals (onl two ofwhich are shown) in said wall 4, their ends being soldered in flanges 22and 24 of said pole pieces I4 and i6, respectively. Headers 2G and 28,of steel or other suit able magnetic metal, are soldered to the two endsrespectively of a cylinder Bit of electrically con ductive non--magneticmetal, such as copper, for example, possessing a relatively highcoefficient of theirnal conductivity, thus forming with said headers anenvelope containing all the parts so far described, and which can beevacuated through a pipe which is then sealed. The flange 2d of polepiece it is spot-welded to said header 28, the other header 26 beingslightly spaced from the pole piece M.

The cathode I! will preferably be of the indi rectly heated thermionictype comprising a hol-- low cylinder of electrically conductive metal,nickel for example, containing a heater wire 34, and the active portion52 of said cathode may be coated with an electronmissive substance, suchas oxides of the alkaline earth metals. The slightly enlarged lower endof said cathode l 5 fits tightly in the lower end of a bore 38 extendingcentrally through said. pole piece it and in alignment with a similarbore ii} in the upper pole piece is. The upper end of said cathode isre" ceived in said bore id of said pole piece l4, said bore is being ofthe same diameter as said bore 38, and the upper end of th cathode beingenlarged to the same extent as its lower end in order to fit said boreill so that the cathode is thus securely centered and electricallyconnected to said pole piece M. The pole piece ma be copper plated toincrease its conductivity. The heater wire 3 extends axially of thecathode. its upper end being connected to the inner surface of theenlarged upper end of said cathode and its other end to a conductor Mconnected to a lead-in conductor 45. From said pole piece it, the heaterwire circuit continues through the header 23 to the lead-conductor 4?.The anode lead-in conductor is shown. at 49 sealed through heater 2%.(See Fig. 3.) A cylindrical magnet 43 for exciting the pole pieces l4and 15 may surround the copper cylinder 30.

If the above described electron discharge device be energized, and thepole pieces Id. and IE be excited by a suitable magnet, such as thatabove referred to, oscillations will be generated in said device whichmay be led out of the device by a coupling loop extending into the anodestructure above the space or resonator cavity between two of said anodearms 8. In accordance with the present invention one end of saidcoupling loop 50 is connected to the inner end of a tubular structurecomprising a conducting pipe 52 (see Fig. 1) extending through anopening 5| in said wall 4 of the anode structure and spaced from theinner wall of said opening, said pipe being hermetically soldered at itsother end around a circular opening through the wall of said header 28.A second conducting pipe 58 is soldered at one end around said opening5| in continuation of said pipe 52. The other end of said loop 50 isconnected to a conductor 54 which extends axially of said two pipes 52and 58 and is sealed through a glass seal 56 carried by said header 28,said conductor 54 forming with said pipes 52 and 58 a coaxial linethrough which the high frequency oscillations generated by the devicemay be conducted to any suitable utilization circuit. In accordance withthe present invention elec-- tricall non-conductive means willpreferably be provided to keep said conductor 54 centered in said pipe.Said means may conveniently consist of a suitable insulating material51, such as polystyrene.

Each pair of anode arms 8 forms with the portion of wall 4 between theman oscillating cavity or cavity resonator. A capacitance exists betweenthe cathode and the end faces of said anode arms and also between theside walls of each cavity resonator. The conductive path around eachcavity resonator aiforded by the walls thereof constitutes aninductance. The anode therefor is so designed and spaced relatively tothe cathode that said inductances and capacitances constitute tunedcircuits.

In accordance with the present invention the device will preferably beassembled as follows:

The anode structure 2, 4, 8, pole pieces 14 and i6, and the supportingrods l8 are first assembled in the proper relative positions they are tooccupy in the completed device and. are then placed in a jig andsoldered together in a suitable furnace and in one operation so as toform a unit. The base assembly comprising the header 28 with theconducting pipes 52 and 58 welded thereto as previously described, andcontaining the conductor 54, sealed in the lower end of said pipe 52,and the conductors 46 and 49 sealed through said header 28, is thensecured to said unit by spot-welding the flange of the pole piece [6centrally to the inner surface of said header 28, after first passingthe upper end of pipe 52 through the opening 5| in said wall 4 of theanode structure and bending the projecting coupling loop 58 so that itshall overhang a cavity resonator, as shown in Figs. 1 and 4. The

cathode H with the heater wire 34 therein and connected thereto, aspreviously described, will also be inserted in proper position in thebores 38 and 48 of the two pole pieces I6 and I5, respectively, beforespot-welding the flange 24 of the pole piece 16 to the inner surface ofsaid header 28. The top header having been welded or sol-- dered to theupper end of the cylindrical casing 30, the lower end of the cylindricalcasing 30 6 0 Number '4 can now be welded to the marginal portion ofsaid header 28 thus completing the assembly of the device.

By assembling the parts in their correct relative positions, as abovedescribed, and then mounting them as a unit in the envelope instead ofseparately in the latter, the correct relative positions of the parts inthe finished article are assured. Owing to the diminutive size of thedevice and the restricted space into which the different parts must bemounted, assembling the parts separately in the casing would be verydifficult and it would be particularly difiicult to insure their beingin their correct relative positions.

Wherever the expression a plurality occurs it is to be constituted asmeaning two or more.

I am aware that the present invention can be embodied in other specificforms without departing from the spirit or essential attributes thereof,and I therefore desire the present description to be considered in allrespects as illustrative and not restrictive, reference being had to theappended claim rather than to the aforesaid description to indicate thescope of the invention.

What is claimed is:

An electron discharge device comprising a cathode, an anode structureincluding a wall having a plurality of electron-receiving portionsadjacent said cathode, a cavity resonator interconnectin each pair ofadjacent electron-receiving portions, a tubular structure extendingthrough an aperture in said wall in spaced relationship to said wall, aconductor extending axially of said tubular structure, an output loopadjacent one of said cavity resonators, one end of said loop beingelectrically connected to said tubular structure and the other end ofsaid loop being connected to said conductor, and insulating meansengaging said conductor and the inner wall of said tubular structure forcentering said conductor in said tubular structure.

CARL W. BECKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Kuhle et al, Feb. 25, 1936 Linder Apr.15, 1941 Von Baeyer Jan. 20, 1942 Helbig Dec.'22, 1942 Linder May 16,1944 White Aug. 20, 1946 Tonks Oct. 22, 1946 Donal, Jr. et al. June 15,1948 FOREIGN PATENTS Country Date Great Britain July 11, 1939 Number

